Methods for laser cutting  and processing tubing to make medical devices

ABSTRACT

A method for making a device includes providing a tubular member which will be formed into the device, masking at least a portion of the inner surface of the tubular member with a removable sacrificial material, selectively removing a portion of the tubular member and sacrificial material using a laser device, and mechanically removing the sacrificial material from the inner surface of the tubular member. Ultrasonic energy could be applied to a workpiece which is being laser cut to prevent any generated slag from welding itself to an exposed surface of the workpiece. A compressed fluid or gas, such as air, could be used to clean the surface of the laser-cut workpiece to remove slag formation which adheres to the surface of the cut workpiece.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part application of U.S. Ser. No. 11/756,305,filed May 31, 2007, the contents of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

The present invention relates generally to methods for laser cutting andprocessing a hollow workpiece, such as a length of tubing. The presentinvention is more particularly directed to methods for fabricatingmedical devices, such as, for example, expandable endoprostheses,commonly known as stents, using processes which help to prevent damageto the workpiece when cutting the workpiece with a laser apparatus andwhen later processing the cut workpiece.

Stents are particularly useful in the treatment and repair of bloodvessels after a stenosis has been compressed by percutaneoustransluminal coronary angioplasty (PTCA), percutaneous transluminalangioplasty (PTA), or removed by atherectomy or other means, to helpimprove the outcome of the procedure and reduce the possibility ofrestenosis.

Stents are generally cylindrically shaped devices which function to holdopen, and sometimes expand, a segment of a blood vessel or otherarterial lumen, such as a coronary artery. Stents are usually deliveredin a compressed condition to the target site and then deployed at thatlocation into an expanded condition to support the vessel and helpmaintain it in an open position.

Prior art stents typically fall into two general categories ofconstruction. The first type of stent is expandable upon application ofa controlled force, often through the inflation of the balloon portionof a dilatation catheter which, upon inflation of the balloon or otherexpansion means, expands the compressed stent to a larger diameter to beleft in place within the artery at the target site. The second type ofstent is a self expanding stent formed from shape memory metals or superelastic nickel titanium alloys (Nitinol), which will automaticallyexpand from a compressed state when the stent is advanced out of thedistal end of the delivery catheter into the blood vessel.

Stents can be formed with strut patterns which when expanded have alarge amount of open space, but when collapsed have little space betweenthe often tortuously shaped struts forming the stent. One method ofmaking a stent includes laser cutting a tubular member or tubing ofsuitable material to create the intricate strut patterns which definethe structure of the stent. Laser cutting generally provides a precisemethod for forming these intricate strut patterns in the tubing used toform the stent. Such patterns require the tubing to be cut through oneside of the wall of the tubing without cutting through the opposite sideof the tubing.

In the past, laser apparatus utilizing pressured air (oxygen) have beenused to cut the tubing. Generally, a laser beam locally heats the tubingmaterial while pressurized air is blown through a small coaxial orificedirectly onto the heated region in order to create a slot or “kerf”through the wall of the tubing.

Laser cutting of a length of tubing generally begins by focusing a laserbeam on a targeted spot on the tubing. The spot is melted and ispreferably vaporized, or at least partially vaporized, by the laserbeam. Once the laser beam burns through the side wall of the tubing, thebeam will usually continue to strike the opposite side wall of thetubing, and may begin to vaporize, or partially vaporize, the oppositeside wall of the tubing. This undesirable burning or partialvaporization of the opposite sidewall is called “burn through” and canresult in the weakening of opposite sidewall. In some cases, burnthrough may result in the workpiece being discarded. The melting andvaporization of the tubing also can form “recast” material, which ismaterial from the tubing that has melted and resolidified on laser-cutsurfaces. The recast material, also referred to as “dross,” may includemetal oxides and impurities which are undesirable in the manufacturingprocess since the recast material must be thoroughly removed from thesurface of the stent. Oxidation can make a stent more susceptible tofailure (e.g., cracking or fracture) during manufacturing or, if notcompletely removed, in use. Additionally, recast material can beparticularly difficult to remove without damaging the thin strutscreated by the laser cutting operation. Therefore, both burn through andformation of recast material presents a formidable problem to the stentmanufacturer.

The problems of laser cutting self-expanding stents made from a materialsuch as Nitinol are further enhanced when pressurized air or oxygen isused to create the cut pattern. Because Nitinol is composed of about 50%titanium, a notoriously reactive metal, the titanium readily reacts withthe oxygen in the air when heated. As a result, the material expelledduring the cutting procedure is predominately comprised of metal oxides,most of which are trapped inside the tubing and adhere to the metallicinner surface of the Nitinol tube. Side walls of the slot or kerf alsobecome oxidized during the cutting process, making the as-cut stent lessductile and thereby more susceptible to cracking or complete fractureduring radial expansion or during other subsequent manufacturing steps.As a result, a laser cut Nitinol work piece must be carefully processedby a number of different cycles of chemical treatment, radial expansion,and heat stabilization to achieve the final stent size.

Any remaining oxidized wall material and other adhered oxide debris mustfirst be removed in order to attain an acceptably smooth surface laterduring electropolishing. This additional clean up procedure can beachieved through a combination of automated grit blasting, manual gritblasting and chemical removal of oxide prior to electropolishing. Somemethods require the physical removal of the recast material using areamer or similar equipment and can often damage the thin struts of thestent. While electropolishing procedures can remove some recastmaterial, often the recast material may be so heavily clad on thesurface of the stent that not all of the recast material can be removedby this process. Additionally, the electropolishing process will removematerial from the struts so it is important that only a small amount ofthe strut surface is actually removed. For example, if theelectropolishing procedure is too long in duration, due to accumulatedrecast material, portions forming the struts of the stent may have toomuch material removed, resulting in a damaged or generally weakenedstent.

Certain methods have developed to deal with the problem caused by burnthrough and the formation of recast material on the workpiece. One suchmethod uses a continuous metal wire run through the tubular workpiece tocreate a “protective barrier” which somewhat helps to prevent the laserbeam from striking the opposite sidewall of the tubing. Another systemutilizes a liquid flushed through the workpiece as it is being cut. Thefluid is usually fed through one end of the tubing and exits through theopposite end of the tubing, along with the newly formed openings in thewall of the tubing created by the laser. The liquid flushes away some ofthe recast material being created by the vaporization of the tubing.However, the presence of this liquid does not always completely blockthe laser beam, which can allow the inside wall of the tubing to beheated and damaged. Additionally, the use of liquid requires additionalequipment for handling the liquid including discharge equipment, catchbasins, waste disposal, and other processing equipment.

It has been anticipated that Nitinol stents could be laser cut using aninert gas such as argon or helium to prevent sidewall oxidation whichwould help prevent cracking or fracturing during subsequent processing.The absence of oxygen in the cutting process also will help to preventthe recast material from being oxidized. However, laser cutting Nitinoltubing utilizing pressurized argon gas typically cannot directly producea finished stent because the expelled melted material formed during thecutting process can become “welded” to the inner wall of the tubing.This welded metallic build up could possibly be removed by laterprocessing including reaming, drilling, electric discharge machining andthe like but with difficulty and risk to the integrity of the workpiece.

What have been needed and heretofore unavailable are improved methodsfor reducing the adverse results caused by burn through along with theelimination of oxidation during the laser cutting process. Also, itwould be beneficial to utilize additional equipment and processes toease in subsequent cleaning, polishing and processing of the cutworkpiece. The present inventions disclosed herein satisfy these andother needs.

SUMMARY OF THE INVENTION

The present invention is directed to methods for laser cutting a tubularworkpiece which helps to reduce the number of post-cutting processingsteps by preventing oxidation and preventing recast from adhering to theworkpiece material during the laser cutting process. The presentinvention prevents oxidation of the workpiece by utilizing a laserapparatus that utilizes an inert gas, such as argon or helium, ratherthan air or oxygen, to create the slots or kerfs which form the patterncut into the workpiece. The absence of oxygen in the cutting processthus prevents the workpiece from being oxidized during laser cutting.The present invention also utilizes a disposable, sacrificial mask whichhelps to prevent damage to the workpiece by covering the surface of theworkpiece as it is being laser cut. The present invention isparticularly beneficial in manufacturing intricately shaped devices froma hollow workpiece, such as a stent.

In one aspect of the invention, the disposable mask can be placed overat least a portion of the inner surface of the tubular member or tubingwhich is being laser cut. In the laser cutting process, recast materialformed during the cutting process is forced through the kerf via thepressurized inert gas and is collected on the surface of the disposablemask, rather than on the inner surface of the tubular member. Tubingmade from Nitinol can be laser cut using an inert gas without the riskof the recast material being welded onto the inner surface of thetubular member. During the cutting operation, both the tubular memberand the disposable mask are simultaneously cut to the same pattern.During cutting, the expelled molten Nitinol collects on the innersurface of the disposable mask instead of directly on the inner surfaceof the tubular member, and afterward the expelled material andsacrificial mask can be removed because neither are strongly affixed tothe inner surface of the Nitinol workpiece. Because the inert gasprevents oxidation of the sidewalls of the tubular member, the presentinvention allows the cut workpiece to be further processed with littleor no need to grit blast tough oxidized material from the stent wallprior to electropolishing.

After the tubular member and sacrificial mask have been laser cut, therewill be a build up of recast material formed along the bottom edges ofthe kerfs and elsewhere along the workpiece. Expelled molten materialfrom the tubular member will collect on the inner surface of thesacrificial mask rather than being directly welded on to the innersurface of the tubular member. However, the recast material must stillbe removed from the laser-cut tubular member prior to electropolishing.

The present invention utilizes a variety of mechanical techniques toremove the sacrificial mask from the tubular member, along with avariety of chemical removal techniques which can be coupled with themechanical techniques to quickly and cleanly remove the dross andsacrificial mask from the inner wall of the formed tubular member.

In one particular aspect of the present invention, the purely mechanicaltechniques for removing the dross and sacrificial mask is to attack thedross only, utilizing equipment which will grind, hone or bead-blast thedross only. Dross also can be removed utilizing a tool such as a wirebrush or reamer. Another way to clean the lased tubular member would beto mechanically attack the sacrificial mask only. Similar mechanicaltechniques could be used to remove the sacrificial mask. Lastly, thesesame techniques could be used to mechanically attack both the dross andsacrificial mask. These various techniques provide simple but usefulmanufacturing steps to separate the lased tubular member from thesacrificial mask and dross.

In other aspects of the present invention, mechanical techniques toseparate the components include employing different material propertiesbetween the lased tubular member and the sacrificial mask. For example,the tubular member and sacrificial mask could be made from differentmaterials having different coefficients of thermal expansion.Application of heat or cold to the tubular member and sacrificial maskcould then be used to break the sacrificial mask away from the lasedtubular member.

In another mechanical procedure, a lased tubular member made from aself-expanding material, such as Nitinol, could be crushed and rolled toallow the tubular member to spring back to shape. Since the sacrificialmask is not superelastic, the crushing and rolling of the tubular membershould break any connection between the sacrificial mask and the tubularmember. Alternatively, the lased tubular member could be expanded,rather than being rolled, thereby causing the sacrificial mask to breakaway from the tubular member.

Still other removal procedures which can be implemented in accordancewith the present invention include mechanically peeling the sacrificialmask from the lased tubular member or mechanically gripping andpulling/pushing the sacrificial mask out of the tubular member. Removalprocedures could alternatively call for the tubular member/sacrificialmask to subjected to vibration, which would break the sacrificial maskfrom the tubular member.

In another aspect of the present invention, the procedure for removingthe sacrificial mask and dross from the lased tubular member wouldutilize a combination of chemical removal techniques with mechanicalremoval techniques, such as the ones addressed above. For example, aftercutting, the lased tubular member and sacrificial mask can be subjectedto a chemical attack which would only attack the tubular member materialtherefore dissolving the dross. A chemical solution would be applied toboth the tubular member and sacrificial mask. The application of thechemical solution is designed to primarily attack the tubular member,rather than the disposable mask material. As such, the chemicals areselected which preferably attack the material of the tubular member,leaving the sacrificial mask material generally unharmed. In one aspectof the invention, the chemical solution attacks the tubular member byetching it. It should be noted that the recast material (especially thethin connection between the sidewall and recast metal) has a very largesurface area to volume ratio and therefore it is much more readilyattacked by the chemical solution than the body of the tubular memberitself. This process of applying a chemical solution which primarilyattacks the material forming the tubular member eliminates or weakensmuch of the recast material formed in the kerfs and elsewhere, therebyallowing the tubular member and the sacrificial mask material to be moreeasily separated.

After the chemical solution has acted on the tubular member, the tubularmember and the sacrificial mask material are mechanically separated.This mechanical separation causes any recast material that is stilladhering to the tubular member to be broken off, leaving the innersurface of the tubular member virtually free of any recast material. Theremoval of the sacrificial material from the inner surface of thetubular member can be performed mechanically, for example, by deviceswhich will break the recast material formed in the kerfs and elsewhere.The mechanical process of removing the sacrificial material from thetubular member can be performed, for example, by inserting a mandrelinto the inner lumen of the disposable mask and twisting the sacrificialmask from the inner surface of the tubular member. Any of the mechanicaltechniques mentioned above could be implemented to remove thesacrificial mask and any remaining dross from the tubular member.

In another aspect of the present invention, the removal process wouldencompass the application of a chemical solution which attacks only thesacrificial mask, leaving the tubular member virtually unharmed. Thechemical attack can either dissolve the sacrificial mask completely, orcould just weaken the sacrificial mask. Any one of a number ofmechanical procedures could then be implemented to remove any remainingportions of the sacrificial mask and dross.

The removal process could encompass the application of chemicals whichattacks both the sacrificial mask and tubular member. In this aspect ofthe invention, a chemical solution could first be applied which attacksor dissolves only the dross, then a second chemical solution could beapplied which attacks only the sacrificial mask. Alternatively, thechemical solution which only attacks the sacrificial mask could beapplied first and later the chemical solution which attacks the drosscould be applied. In yet another removal procedure, a chemical solutionwhich simultaneously attacks both the tubular member and sacrificialmask could be applied. In one scenario, the chemical solution couldcompletely dissolve the sacrificial mask and dross. Alternatively, ifthe solution only weakens the dross and sacrificial mask, any remainingdross and mask material could be mechanically removed using any of themechanical techniques mentioned above.

In another aspect of the invention, the disposable mask can take theshape of a tubular sleeve that is placed snugly against the insidesurface of the tubular member. The disposable mask preferably assumesthe form of a thin wall tube whose outer diameter closely matches theinner diameter of the tubular member. Alternatively, the mask may becomprised of a flat foil that is rolled into a cylinder and theninserted into the tubular member. In other aspects, the disposable maskmay be produced through the build-up of material such as byelectroplating, plasma spray, physical vapor deposition, chemical vapordeposition and the like. However, the disposable mask material shouldnot become metallurgically bonded or otherwise so strongly affixed tothe tubular member that the two components cannot be easily separatedfrom each other after laser cutting. Additionally, the disposable maskand the work piece should be made from dissimilar materials that do noteasily weld or bond to one another.

In one particular aspect of the present invention, steel or stainlesssteel is used to form the disposable mask when the workpiece is beingformed from binary nickel-titanium or a nickel-titanium alloy due to theinherent metallurgical incompatibility of these materials. Thedisposable mask also could be made from any suitable material capable ofwithstanding the temperatures of the expelled molten Nitinol material,for example, ceramics, metals, composites, or high temperature polymers.

In another particular aspect of the present invention, carbon steel canbe used to form the disposable mask when the workpiece is being formedfrom binary nickel-titanium or a nickel-titanium alloy due to theinherent metallurgical incompatibility of these materials. In oneaspect, the disposable mask can be made from a carbon steel strip whichis rolled or coiled into a sleeve that fits within the lumen of thetubular member. The strip of carbon steel creates a coiled sleeve whichcan expand radially within the lumen of the tubular member to ensurethat a tight fit is made between the surfaces of the coiled sleeve andtubular member.

In another aspect of the present invention, the coiled sleeve andtubular member could be selectively lased removing a portion of thetubular member and coiled sleeve. After the laser cutting step, an acidetchant solution could be applied to the tubular member and coiledsleeve to erode the coiled sleeve. Any portion of the coiled sleevewhich remains after the laser cutting would be eroded by the acidetchant. In another aspect, the acid etchant could be heated prior toapplication of the acid etchant to the tubular member and coiled sleeve.The acid etchant can be a mixture of hydrofluoric acid and nitric acid.In one aspect, the application of the acid etchant can be performed byplacing the tubular member and coiled sleeve into a bath containing theacid etchant The tubular member can be further processed by rinsing itwith water and placing it in an ultrasonic bath containing alcohol.

In another aspect of the present invention, the process of making thedevice includes placing a sleeve made from a removable sacrificialmaterial within the lumen of the tubular sleeve and co drawing thetubular member and sleeve together. In this aspect of the invention, theco drawing causes the surfaces of the sleeve and tubular member to comeclose together such that small spaces or gaps between the surfaces areeliminated or greatly reduced. The co drawing of the tubular member andsleeve should be controlled to prevent the surfaces from molecularlybonding to each other. The tubular member and sleeve could then be lasercut with any remaining portion of sleeve being removed from the tubularmember. In one aspect, the removal of any remaining portion of thesleeve can be done mechanically. In another aspect, the removal can bedone chemically. In one particular aspect, any remaining portion of thesleeve cab be chemically removed from the tubular member by applying achemical solution to the tubular member and sacrificial material for atime duration in which the chemical solution primarily attacks thesacrificial material.

The pressurized inert gas used with the laser apparatus could be argonor helium as these two inert gases are economical and commerciallyavailable. However, it should be understood that the laser cutting ofthe tubular metallic work piece could utilize any inert or nonreactive,oxygen-free gas to prevent oxidation during the cutting process.

The use of the present method in forming a medical device, such as astent, helps to minimize the need for grit blasting or otherwisechemically removing the oxidized cast material prior to electropolishingsince air or oxygen is no longer used in the laser cutting process. Theuse of the inert gas eliminates the possibility that the sidewalls ofthe tubular member and recast material will become oxidized during lasercutting. As a result, the elimination of sidewall oxidation helps toprevent cracking or fracturing of the stent during use and eliminatessome of the subsequent processing which would be otherwise be needed toremove the oxidized material from the tubular member. As a result, theformed workpiece can be sent for electropolishing without the need foradditional processing which could break or irreparably damage thefragile struts which form the stent.

In yet another aspect of the present invention, the process of makingthe device includes applying ultrasonic energy to the tubular member asit is being laser cut into the desired shape of the workpiece. Theapplication of ultrasonic energy to the tubular member helps top preventslag from solidifying on the inner surface of the tubular member. Theapplication of ultrasonic energy to the tubular member could beperformed when the tubular member is being cut utilizing conventionallaser cutting techniques already known in the art or could be used inconjunction with the novel sacrificial masks and processes disclosedherein.

In one particular aspect of the present invention, ultrasonic energycould be applied using an ultrasonic source, such as an ultrasonictransducer which includes a bushing that contacts the outer surface ofthe tubular member as it is being cut. The use of ultrasonic energy canbe used in any laser cutting operation in which slag is formed andbecomes problematic to the manufacturer since the slag will becomedeposited on a surface of the tubular member and will be required to beremoved during subsequent processing.

In yet another aspect of the present invention, cleaning and polishingof the cut workpiece can be accomplished without application ofexcessive forces which could otherwise damage the often intricately cutworkpiece. In this aspect, the cut tubular workpiece could be subjectedto compressed air which will cause any slag affixed to the surface to bequickly removed. In one particular aspect, a mounting fixture having anumber of outlet openings could be utilized to supply compressed air inthe form of individual jets to the surface of the tubular workpiece. Acompressed air supply would be connected to the mounting tube to supplythe compressed air to the mounting fixture. The tubular workpiece wouldbe slidable over the mounting fixture to allow the surface to besubjected to multiple jets of compressed air which will break most bondsbetween the slag and the surface of the workpiece. This process mayeliminate the need to apply excessive force to the workpiece to breakthe slag from the surface. As a result, a greater yield of finishedworkpieces can be accomplished in less time that is normally needed toremove the slag using manual techniques.

These and other advantages of the present invention become more apparentfrom the following detailed description of the invention, when taken inconjunction with the accompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a schematic of a method of making adevice, such as a stent, from a tubular member using a laser devicewhich uses an inert gas to assist in the cutting process;

FIG. 2 is an end view showing the resulting formation of recast materialon the inside surface of a tubular member when the laser cuts one sideof the tubular member;

FIG. 3 is schematic side view showing the laser cutting of the tubularmember mounted on a disposable sacrificial mask;

FIG. 4 is a side elevational view showing the resulting build up ofrecast material or “slag” along the bottom edge of the slot or kerfformed on the tubular member which must be removed prior toelectropolishing;

FIG. 5 is a side elevational view showing the disposable mask and recastmaterial removed from the inner surface of the tubular member;

FIG. 6 is a perspective view of a carbon steel sleeve which is rolled tocreate a disposable sacrificial mask in accordance with the presentinvention;

FIG. 7 is a perspective view of the rolled carbon steel sleeve of FIG. 6which shows a portion of overlap of the sleeve;

FIG. 8 is a perspective view of a tool which draws down the rolledcarbon steel sleeve of FIGS. 6 and 7 in order to fit within a tubularmember;

FIG. 9 is a cross-sectional view of the tool of FIG. 8;

FIG. 10 is a cross-sectional elevational view showing the rolled sleeveof FIGS. 6 and 7 being drawn down by the tool of FIGS. 8 and 9 in orderfit the rolled sleeve into a tubular member;

FIG. 11 is a cross-sectional view showing a disposable sacrificial maskand tubular member which undergo a co-drawing process prior to lasercutting;

FIG. 12 is a cross-sectional schematic representation showing a systemwhich applies ultrasonic energy to the tubular member during lasercutting;

FIG. 13 is a cross-sectional view showing the system of FIG. 12 alongline 13-13;

FIG. 14 is a top view showing a compressed air mounting fixture whichdischarges multiple jets of air to clean a tubular workpiece; and

FIG. 15 is a top view showing a laser-cut tubular workpiece disposed onthe compressed air mounting fixture of FIG. 14.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawing in which reference numerals represent likeor corresponding elements across the drawings, and particularly FIGS. 1and 3-5, a method of making a device from a hollow tubular member 10 isgenerally disclosed. The present invention relates generally to methodsfor laser cutting a length of hollow tubing, or as is it referred toherein a “tubular member,” to form a device, typically a medical device,such as a stent. While most workpieces formed in accordance with thepresent invention are in the form of a tubular member having a circularcross section, the tubular member could have a non-circular crosssection as well. For example, the tubular member could have arectangular, oval, square, and the like cross section, if desired.Moreover, the invention is not limited to forming stents and has a wideapplication with respect to other laser cut medical devices andnon-medical products, particularly products which require a highprecision pattern that is cut utilizing a laser cutting process.

Referring specifically to FIG. 1, in one particular form of the presentinvention, the method includes providing a tubular member 10 which willbe formed into the finished device. The tubular member 10 has an outersurface 12 along with an inner surface 14. The tubular member 10 is madefrom a particular material suitable for the finished device and is to belaser cut, as will be described herein, to generally form the desiredpattern and shape of the finished workpiece. The present invention isparticularly useful in cutting a tubular member made from anickel-titanium alloy (Nitinol) or a ternary nickel-titanium alloy suchas nickel-titanium-platinum. When a stent is being fabricated, thetubular member will be laser cut to remove portions of the tubularmember to create the desired strut patterns of the stent. It should beappreciated that additional processing of the workpiece may be neededafter initial laser cutting to achieve the final finished product.

As can be seen in FIG. 1, the tubular member 10 is shown in contact witha disposable mask made from a sacrificial material that will besimultaneously laser cut with the tubular member 10, but will be laterremoved in subsequent processing. This disposable mask, shown in thisparticular embodiment of the invention as a masking sleeve 16, is placedwithin the tubular member 10 to cover or mask at least a portion of theinner surface 14 of the tubular member 10. This masking sleeve 16includes an outer surface 18 and an inner surface 20. The masking sleeve16 is placed snugly against the inside surface 14 of the tubular memberand can be later removed from contact with the tubular member 10. Thedisposable mask can be formed as a thin wall tube whose outer diameterclosely matches the inner diameter of the tubular member 10. Generally,the disposable mask can have the same length, or can be larger orsmaller than the length of the tubular member, depending, of course, onthe amount of laser cutting to be performed on the tubular member 10. Asis depicted in FIG. 1, the length of the masking sleeve 16 is longerthat the length of the tubular member 10.

The method further includes the cutting of the tubular member 10 andmasking sleeve 16 by laser cutting apparatus 22, shown schematically inthe drawing figures. In one aspect of the present invention, the lasercutting apparatus 22 utilizes a pressurized inert gas, such as argon orhelium, rather than air or oxygen, to create the slots or kerfs 24extending through the wall of the tubular member 10 and masking sleeve16. In the method of the present invention, both the tubular member 10and masking sleeve 16 are cut simultaneously by the laser cuttingapparatus 22. Generally, as is schematically depicted in FIG. 3, a laserbeam 26 locally heats the tubular member 10 and masking sleeve 16 whilethe pressurized inert gas, depicted by arrow 28, is blown through asmall coaxial orifice 30 directly onto the heated region in order tocreate the slots or kerfs 24.

Laser cutting of the tubular member 10 and masking sleeve 16 generallybegins by focusing a laser beam on a targeted spot on the tubing. Thespot is melted by the laser beam while the pressurized inert gas forcesthe molten material through the walls of the tubular member and maskingsleeve 16 to form the kerf 24. The tubular member 10 and sleeve 16 aremoved by an automated mechanism of the laser cutting apparatus to createthe desired pattern. Once the laser beam burns through the side wall ofthe tubular member 10 and masking sleeve 16, the laser beam couldpossibly continue to strike the opposite inside surface of the tubularmember. However, the masking sleeve 16 covers the inner surface of thetubular member 10, thus preventing any damage to the tubular member. Inthe laser cutting process, recast material 32 which is forced throughthe kerf via the pressurized inert gas is collected as a disposable masson the masking sleeve 16, rather than being “welded” to the innersurface 14 of the tubular member 10. In this aspect of the invention,the masking sleeve 16 forms a protective barrier for the inner surface14 of the tubular member 10. FIG. 2 shows how the recast material wouldstrike and damage the inner surface of the tubular member 10 if adisposable mask is not present. Also, since the inert gas preventssidewall oxidation, the method of the present invention allows the cutwork piece to be processed downstream without the need for substantialautomated or manual grit blasting prior to electropolishing.

As is best depicted in FIG. 4, the laser cutting process not onlyresults in the formation of recast material 32 disposed as bulk waste onthe inner surface 20 of the masking sleeve 16, but also results in theformation of recast droplets 34 near the lower portion of the kerf 24.These recast droplets 34 cause portions of the tubular member 10 andmasking sleeve 16 to somewhat bond together, forming an unwanted meldedstructure which must be removed from the tubular member 10 beforeadditional processing proceeds. These recast droplets 34 are primarilysolidified droplets of the material forming the tubular member 10.

The present invention utilizes a variety of mechanical techniques toremove the sacrificial mask and dross from the tubular member, alongwith a variety of chemical removal techniques which can be coupled withthese mechanical techniques to quickly and cleanly remove the dross andsacrificial mask from the inner wall of the laser cut tubular member.

In one particular post-cutting procedure, the purely mechanicaltechniques for removing the dross and sacrificial mask is to attack thedross only, utilizing equipment which will grind, hone or bead-blast thedross only. For example, dross also can be removed utilizing a tool suchas a wire brush or reamer. Another way to clean the lased tubular memberwould be to mechanically attack the sacrificial mask only. Similarmechanical removing techniques could be used to remove the sacrificialmask. Lastly, these same techniques could be used to mechanically attackboth the dross and sacrificial mask. These various techniques providesimple but useful manufacturing steps to separate the lased tubularmember from the sacrificial mask and dross.

The process of mechanically separating the disposable mask from thetubular member can use, for example, any type of device which will breakthe recast droplets and the contact between the surfaces of the tubularmember and disposable mask. For example, the mechanical process ofremoving the sacrificial material from the tubular member can beperformed by inserting a mandrel (not shown) into the lumen of themasking sleeve. The mandrel can be twisted causing the disposable maskto break contact with the inner surface 14 of the tubular member 10. Thetwisting action of the mandrel helps to peel the disposable maskingmaterial from the inner surface of the tubular member and break the bondcreated by the recast material and droplets. The surface of the mandrelcould include prongs, flutes, knurling or other friction enhancingstructure which increases frictional contact between the mandrel anddisposable mask. It should be appreciated that other means formechanically removing the disposable mask from the tubular member can beutilized in accordance with the present invention.

Another particular mechanical technique for removing the sacrificialmask and dross from the tubular member would require the separation ofthe components by employing different material properties between thelased tubular member and the sacrificial mask. For example, the tubularmember and sacrificial mask could be made from different materialshaving different coefficients of thermal expansion. For example, heat orcoldness could be applied to the cut work piece to cause the tubularmember to either expand or contract, which should break the sacrificialmask away from the lased tubular member. Alternatively, the sacrificialmask could be made from a material which will expand or contract uponapplication of heat or coldness to cause the mask to break away from thetubular member.

In another mechanical procedure, a lased tubular member made from aself-expanding material, such as Nitinol, could be crushed and rolled toallow the tubular member to spring back to shape. The sacrificial maskcould be made from a material which is comparatively not very elastic,so that the crushing and rolling of the tubular member should break anyconnection between the sacrificial mask and the tubular member.Alternatively, the lased tubular member could be expanded, rather thanbeing rolled, which again should cause the sacrificial mask to breakaway from the tubular member.

Still other removal procedures which can be implemented in accordancewith the present invention include mechanically peeling the sacrificialmask from the lased tubular member or mechanically gripping andpulling/pushing the sacrificial mask out of the tubular member. A reameror mandrel could be used to grip the inside surface of the sacrificialmask to allow a technician to pull or push the mask from the tubularmember. Other tools could be implemented as well to accomplish this typeof mechanical removal. Additionally, removal procedures couldalternatively call for the laser cut tubular member/sacrificial mask tosubjected to vibration, which would break the sacrificial mask from thetubular member.

In another aspect of the present invention, the procedure for removingthe sacrificial mask and dross from the lased tubular member wouldutilize a combination of chemical removal techniques with mechanicalremoval techniques, such as the ones addressed above, to achieve a cleanworkpiece which is ready for electropolishing. For example, aftercutting, the lased tubular member and sacrificial mask can be subjectedto a chemical attack which would only attack the tubular member itself,i.e. the dross. A chemical solution would be applied to both the tubularmember and sacrificial mask. The application of the chemical solution isdesigned to primarily attack the tubular member, rather than thedisposable mask material. As such, the chemicals are selected whichpreferably attack the material of the tubular member, leaving thesacrificial mask material generally unharmed. In one aspect of theinvention, the chemical solution attacks the tubular member by etchingit.

The process for removing the recast material and droplets from thetubular member requires a chemical solution to be applied to both thetubular member 10 and masking sleeve 16. The chemical solution can bedirectly applied to the tubular member 10 and masking sleeve 16 or thecomponents could be dipped into a bath containing the chemical solution.The chemical solution is designed to primarily attack the tubular member10, leaving the masking sleeve unharmed. It should be noted that therecast droplets 34 have a very large surface area to volume ratio andtherefore they are much more readily attacked by the chemical solutionthan the larger body of the tubular member 10 itself. This process ofapplying a chemical solution which primarily attacks the tubular member10 eliminates or weakens much of the recast droplets 34, therebyallowing the tubular member 10 and the masking sleeve 16 to be moreeasily separated.

After the chemical solution has acted on the tubular member, the tubularmember and the sacrificial mask material can be further processed, ifneeded, using mechanically separation procedures. This mechanicalseparation causes any recast material that is still adhering to thetubular member to be broken off, leaving the inner surface of thetubular member virtually free of any recast material. After the chemicalsolution is applied to the tubular member 10 and masking sleeve 16 andthe recast material is weakened, the tubular member and the maskingsleeve 16 should be relatively easy to separate using mechanicaltechniques. Since the masking sleeve is virtually unharmed by thechemical solution, it remains stiff and capable of breaking the recastmaterial formed at the kerfs when twisted away from the tubular member.Any recast material or droplets 34 that still adhere to the tubularmember 10 will be broken off, leaving the inner surface 14 of thetubular member 10 virtually free of any recast material.

The removal of the sacrificial material from the inner surface of thetubular member can be performed mechanically, for example, by deviceswhich will break the recast material formed in the kerfs and elsewhere.The mechanical process of removing the sacrificial material from thetubular member can be performed, for example, by inserting a mandrelinto the inner lumen of the disposable mask and twisting the sacrificialmask from the inner surface of the tubular member. Any of the mechanicaltechniques mentioned above could be implemented to remove thesacrificial mask and any remaining dross from the tubular member, afterthe chemical application has been completed.

In another aspect of the present invention, the process of removing themask and dross from the tubular member would encompass the applicationof a chemical solution which attacks only the sacrificial mask, leavingthe tubular member virtually unharmed. The chemical attack can eitherdissolve the sacrificial mask completely, or could just weaken thesacrificial mask. Any one of a number of mechanical procedures couldthen be implemented to remove any remaining portions of the sacrificialmask and dross.

The removal process could encompass the application of chemicals whichattacks both the sacrificial mask and tubular member. In this process, achemical solution could first be applied which attacks or dissolves onlythe dross. Thereafter, a second chemical solution could be applied whichattacks only the sacrificial mask. Alternatively, the chemical solutionwhich only attacks the sacrificial mask could be applied first and laterthe chemical solution which attacks the dross could be applied. In yetanother removal procedure, a chemical solution which simultaneouslyattacks both the tubular member and sacrificial mask could be applied.In one scenario, the chemical solution could completely dissolve thesacrificial mask and dross, eliminating the need for any furthermechanical separation. Alternatively, if the chemical solution onlyweakens the dross and sacrificial mask, any remaining dross and maskmaterial could be mechanically removed using any of the mechanicaltechniques mentioned above.

The use of the present method in forming a medical device, such as astent, reduces the amount of grit blasting or chemical removal due tothe lack of oxidized cast material since air or oxygen is no longer usedin the laser cutting process. Again, the use of the inert gas eliminatesthe possibility that the sidewalls or the recast material will beoxidized during the laser cutting step. As a result, the elimination ofsidewall oxidation helps to prevent cracking or fracturing of the stentduring use and reduce or even eliminates some of the subsequentprocessing which would be otherwise utilized in order to remove theoxidized material from the tubular member. As a result, the formed stentcan be sent for electropolishing without the need for additionalprocessing, or with only a minimal amount of mechanical processing,which reduces the chance of breaking or irreparably damaging the oftenfragile struts forming the stent.

Although the sacrificial mask is disclosed herein as a disposablemasking sleeve, it should be appreciated that other forms andconfigurations of a disposable sacrificial mask could be used inaccordance with the present invention. For example, the mask may becomprised of a flat foil that is rolled into a cylinder and theninserted into the tubular member. Additionally, the disposable maskcould be produced through the build-up of material on the inner surfaceof the tubular member by such methods as electroplating, plasmaspraying, physical vapor deposition, chemical vapor deposition and thelike. However, it is important that the disposable sacrificial maskmaterial does not become metallurgically bonded or otherwise so stronglyaffixed to the tubular member that the two components cannot be easilyseparated from each other after laser cutting and the application of themechanical and/or chemical processing of the cut workpiece. Thus, thedisposable mask and the tubular member should preferably be made fromdissimilar materials that do not easily weld or bond to one another. Inone particular method of the present invention, steel or stainless steelcan be used to form the disposable mask when a Nitinol tubular member isbeing fabricated because of their inherent metallurgicalincompatibility. For example, the disposable mask could be formed fromany material capable of withstanding the temperatures of the expelledmolten material, such as ceramics, metals, composites, or hightemperature polymers. Other suitable metals include steel, copper,magnesium, nickel, cobalt, molybdenum, tantalum, niobium, titanium,zirconium, tin, iron, or any other alloy based on these metals.

The pressurized inert gas used with the laser cutting apparatus includeargon or helium as these two inert gases are economical and commerciallyavailable. However, it should be understood that the laser cuttingapparatus could utilize any inert gas to prevent the work piece fromoxidizing. Since argon and helium gases are more readily availablecommercially, these inert gases may serve to be more economical from acost standpoint.

One particular method of chemically attacking the tubular member resultsin the material forming a tubular member to be etched away to weaken anyrecast material remaining on the workpiece. In this particular method ofthe present invention, a nickel-titanium or a ternary nickel-titaniumalloy is the material used to form the tubular member and stainlesssteel is used to form the disposable mask. The tubular member and maskcan be immersed in a solution of approximately 3% hydrofluoric acid (HF)and 50% nitric acid to chemically etch the recast material formed by thetubular member to help break the strength of the bond created by therecast material. The acid can rapidly etch away at the nickel-titaniumalloy while the stainless steel disposable mask remains relativelyundamaged. In this aspect of the invention, the acid will leave thestainless steel material relatively unharmed. The submersion of thesetwo components in the hydrofluoric acid can be for a time duration fromapproximately 30-45 seconds, after which the components are removed. Ifneeded, the mechanical process of removing the disposable mask from thetubular member can then be performed. In another variation, a steelsleeve could be used and the aforementioned HF-nitric solution could beused to simultaneously and completely dissolve both the steel sleeve andnitinol dross in only 10-20 seconds. This embodiment is particularlyuseful when the workpiece is particularly long or delicate thereforemaking the mechanical removal of the sleeve difficult. It should beappreciated that other chemical solutions could be utilized inaccordance with the present invention. For example, the chemicalsolution can be acidic, alkaline, or any other chemically reactive agentwhich preferably attacks the tubular member rather than the disposablemask material or simultaneously attacks both. The strength of thechemical solution and the time duration that the chemical solutionremains on the components will depend, of course, on the type ofmaterials used for the tubular member and disposable mask and the typeof chemical utilized.

Referring now to FIGS. 6-10, the disposable mask can be made from astrip of material which is rolled or coiled into a sleeve 36. Thiscoiled sleeve 36, in turn, fits within the lumen of the tubular member10 (FIG. 10). The strip of carbon steel creates a coiled sleeve 36having an outer surface 38 which contacts the inner surface 14 of thetubular member 10. The coiled sleeve 36 is biased somewhat so that itcan expand radially within the lumen of the tubular member 10 to ensurethat a tight fit is made between the surface 30 of the coiled sleeve 36and the surface 14 of the tubular member 10. This coiled sleeve 36 canbe used in any of the method disclosed herein.

As can be seen in FIG. 7, there is a slight overlap 40 of materialforming the coiled sleeve 36. This overlap 40 allows the sleeve 36 toexpand radially outward to contact the inner surface of variously sizedtubular members. In this aspect, the coiled sleeve can be used in anumber of tubular members having different diameters. In this fashion,the coiled sleeve will expand to the particular inner diameter of thetubular member in which it is placed. Thus, the use of a coiled sleeveeliminates the need to manufacture individually sized sleeves for usewith particularly sized tubular member. Hence, one coiled sleeve can beplaced in a number of different sized tubular members. While theparticular embodiment of the coiled sleeve 36 of FIGS. 6 and 7 shows anoverlap 40 ranging about 20° of the full 360° of the circle forming thediameter of the sleeve, it should be appreciated that more or less of anoverlap 40 could be used on the coiled sleeve 36 as well. This overlap40 represents the amount of material which overlaps when the coiledsleeve is in its maximum outside diameter. As will be discussed below,this maximum outside diameter can be reduced to a minimum outsidediameter by applying force to coiled sleeve.

A tool 42, shown in FIGS. 8-10, can be used to place the coiled sleeve38 within the lumen of the tubular member 10. This tool 42 is simply astructural member having two lumens extending therethrough. The firstlumen 44, is used to hold the tubular member 10 as is shown in FIG. 10.The second lumen 46, is used to move the coiled spring into the lumen ofthe tubular member 10. In this regard, this second lumen may be taperedso that a larger diameter is located at the opening 48 through which thecoiled sleeve is inserted. The second lumen tapers to a smaller diameterwhich causes the coiled sleeve to contract to a smaller diameter as itis further inserted into the second lumen 46. In turn, the smallerdiameter of this second lumen 46 draws the coiled sleeve down toproperly fit within the lumen of tubular member 10, as is shown in FIG.10. A plunger (not shown) could be applied to the end of the coiledsleeve to help push the coiled sleeve 36 into the tubular member. Oncethe coiled sleeve is placed within the lumen of the tubular member 10,it will radially expand to create force that maintains tight contactbetween the surface 38 of the sleeve 36 and the inner surface 14 of thetubular member 10. It should be appreciated that other tools and methodscould be utilized to place the coiled sleeve within the lumen of thetubular member.

In another particular aspect of the present invention, carbon steel canbe used to form the coiled sleeve 36, although other material listedabove could also be to create the sleeve. In one particular method ofmaking a device, the coiled sleeve could be placed within the lumen ofthe tubular member. The coiled sleeve 36 and tubular member 10 could beselectively lased removing a portion of the tubular member and coiledsleeve. After the laser cutting step, an acid etchant solution could beapplied to the tubular member and coiled sleeve to erode the coiledsleeve. Any portion of the coiled sleeve which remains after the lasercutting would be eroded by the acid etchant. The acid etchant could beheated prior to application of the acid etchant to the tubular memberand coiled sleeve. The acid etchant can be a mixture of hydrofluoricacid and nitric acid. In one aspect, the application of the acid etchantcan be performed by placing the tubular member and coiled sleeve into abath containing the acid etchant The tubular member can be furtherprocessed by rinsing it with water and placing it in an ultrasonic bathcontaining alcohol.

In one particular example, a strip of 0.0003 inch thick carbon steelhaving a width of about 0.33 inches is rolled into a tubular shape, asshown in FIG. 7. The length of the piece is about 24-27 inches to matchthe length of the nitinol tubing used to create the device. In thiscase, the device to be created is a self-expanding stent. The width ofthe strip is sufficient to achieve a coiled sleeve having an outsidediameter of about 0.1005 inches with about a 20° overlap when coiled inits maximum outside diameter. The coiled sleeve can be rolled or coiledin order to achieve a minimum outside diameter of about 0.095 inches.Thus, the range of expected inside diameters for the nitinol tubingwould be from 0.095 to 0.1005 inches. It should be appreciated that thevarious sizes of the strips used to create the coiled sleeves willdepend upon the various size of the tubular member which will eventuallybe formed into the desired device.

In another aspect of the present invention, the process of making thedevice includes placing a sleeve made from a removable sacrificialmaterial within the lumen of the tubular sleeve and co drawing thetubular member and sleeve together. FIG. 11 schematically shows thesleeve 16 and tubular member being drawn together through a die 50.Still other ways of co drawing the sleeve and tubular member can beachieved. In this aspect of the invention, the co drawing causes thesurfaces of the sleeve and tubular member to come close together suchthat small spaces or gaps between the surfaces are eliminated or greatlyreduced. The co-drawing of the tubular member and sleeve should becontrolled to prevent the surfaces from molecularly bonding to eachother. The tubular member and sleeve could then be laser cut with anyremaining portion of sleeve being removed from the tubular member. Inone aspect, the removal of any remaining portion of the sleeve can bedone mechanically. In another aspect, the removal can be donechemically. In one particular aspect, any remaining portion of thesleeve cab be chemically removed from the tubular member by applying achemical solution to the tubular member and sacrificial material for atime duration in which the chemical solution primarily attacks thesacrificial material. The sleeve can be made from any of the materialslisted above.

Referring now to FIGS. 12 and 13, another system 60 for dealing with theproblems associated with molten slag adhering to the workpiece isdisclosed. The system 60 utilizes the application of ultrasonic energyto the tubular member 10 as it is being laser cut to help prevent anyslag from solidify or strongly adhering to an exposed surface of thetubular member. The system 60 includes a laser cutting apparatus 62,shown schematically in the drawing figures, along with an apparatus 64for applying ultrasonic energy to the tubular member 10 as the tubularmember 10 is being laser cut. The ultrasonic apparatus uses highfrequency energy to vibrate both the liquidified slag and the tubularmember 10 to produce reduce the ability of the slag from stronglyadhering to the exposed portions of the tubular member. When liquids areexposed to these high frequency vibrations, both physical and chemicalchanges occur as a result of a physical phenomenon, known as cavitation.Cavitation is the formation, expansion, and implosion of microscopic gasbubbles in liquid as the molecules in the liquid absorb ultrasonicenergy. If the vibration is sufficiently intense, it should break theattractive forces in the existing molecules of the slag and reduce itsability to bond to a surface.

In this aspect of the present invention, the laser cutting system 60 isshown using a conventional laser cutting apparatus 62 which utilizes airor oxygen to create the slots or kerfs extending through the wall of thetubular member 10. Additionally, the laser cutting apparatus 62 couldpressurized inert gas, such as argon or helium, as is disclosed herein.In accordance with the present invention, still other laser cuttingequipment could also be used to cut the tubular member 10.

Generally, as is schematically depicted in FIGS. 12 and 13, a laser beam66 locally heats the tubular member 10 while the pressurized medium,depicted by arrow 68, is blown through a small coaxial orifice 70directly onto the heated region in order to create the slots or kerfs72. During the cutting process, slag 74 will form and will adhere to anyexposed surface of the tubular member. The ultrasonic energy apparatus64 helps to prevent this from occurring by applying ultrasonic energydirectly to the tubular member 10, and any generated slag 74, to helpprevent the slag from solidifying on any exposed surface of the tubularmember 10.

As is shown schematically in FIGS. 12 and 13, the ultrasonic energygenerating apparatus 64 includes an ultrasonic transducer 76 which iscoupled to a bushing 78. This bushing 78 is, in turn, coupled to thetubular member 10 which will be laser cut by the laser apparatus 62.When subjected to ultrasonic energy, the slag 74 should eitherharmlessly fall from the surface of the tubular member or should beminimally bonded to the tubular member 10. In other words, theultrasonic energy will help to prevent the slag 74 from “welding” itselfto the surface of the tubular member 10. If the slag 74 becomes onlyminimally bonded, it should be easier to remove from the surface of thetubular member 10 using, for example, mechanical and/or chemical removaltechniques, such as those described above.

The system 60 also utilizes an internal mandrel 80, or other component,which could be placed within the lumen of the tubular member 10 to helpcatch some of the slag 74 before it hits an exposed surface of thetubular member. The mandrel 80 can be made, for example, from copper.Additionally, in the method and system disclosed in FIGS. 12 and 13,only the tubular member 10 is shown being cut by the laser cuttingapparatus 62. It should also be appreciated that a sacrificial mask,made in accordance with the present invention, could also be used withthe tubular member 10 to further prevent slag from adhering to thefinished workpiece.

The present embodiment shows the ultrasonic energy generating apparatus64 as a simple transducer/bushing assembly. However, it will beappreciated by those skilled in the art that other structures could beutilized to apply the ultrasonic energy to the tubular member 10 as itis being laser cut without departing from the spirit and scope of thepresent invention. For these reasons, the present invention is notlimited to the ultrasonic energy generating apparatus disclosed in thethis particular embodiment.

Referring now to FIGS. 14 and 15, another apparatus which can be used inpost-cutting procedures is disclosed. These figures show a compressedair mounting apparatus 90 which can be used to clean the surface of thetubular member 10 of slag and other impurities after the tubular member10 has been cut. The compressed air mounting apparatus includes a lengthof tubing 92 having numerous outlet openings 94 which are in fluidcommunication with the lumen (not shown) of the tubing 92. One end 96 ofthe tubing 92 is coupled to a fitting 98 which is, in turn, attached toa compressed air supply 100. The other end 102 of the tubing 92 can beclosed.

In use, the compressed air supply 100 provides an amply supply ofcompressed air which shoots out of the outlet openings 94 to createmultiple jets of air which strike the surface of the laser-cut tubularmember 10, shown mounted on the tubing 92 of the apparatus 90 in FIG.15. The laser-cut tubular member 10 would be slidable on the tubing 92so that the jets of air will strike the surface to remove any slag 104or foreign particles (sometimes referred to as “islands”). The apparatus90 could be encased within a housing 106 to contain the particles ofslag 104 which will be blown off of the workpiece. It should beappreciated that other gases and fluids besides air could be used as themedium for this apparatus 90.

While the invention has been illustrated and described herein, in termsof methods for fabricating a medical device, such as an intravascularstent, it will be apparent to those skilled in the art that the methodscan be used with other devices. Further, other modifications andimprovements can be made without departing from the scope of the presentinvention.

1-14. (canceled)
 15. A method for making a device, the methodcomprising: providing a tubular member with an inner lumen which will beformed into the device; placing a sleeve made from a removablesacrificial material within the lumen of the tubular sleeve; co drawingthe tubular member and sleeve together such that the surfaces of thesleeve and tubular member contact each other but are not molecularlybond to each other; selectively removing a portion of the tubular memberand sacrificial material using a laser device; and removing anyremaining portion of the sleeve from the tubular member.
 16. The methodof claim 15, wherein any remaining portion of the sleeve is mechanicallyremoved from the tubular member.
 17. The method of claim 15, wherein anyremaining portion of the sleeve is chemically removed from the tubularmember.
 18. The method of claim 15, wherein the tubular member is madefrom a nickel titanium alloy.
 19. The method of claim 15, wherein codrawing of the sleeve and tubular member reduces any gaps that wereexisting between the surface of the sleeve and the surface of thetubular member.
 20. The method of claim 17, wherein any remainingportion of the sleeve is chemically removed from the tubular member byapplying a chemical solution to the tubular member and sacrificialmaterial for a time duration in which the chemical solution primarilyattacks the sacrificial material.
 21. A method for making a device, themethod comprising: providing a tubular member which will be formed intothe device; applying ultrasonic energy to the tubular member; andselectively removing a portion of the tubular member material using alaser device while the ultrasonic energy is being applied to the tubularmember.
 22. The method of claim 21, wherein an ultrasonic transducer iscoupled to the tubular member to apply the ultrasonic energy to thetubular member.
 23. A method for making a device, the method comprising:providing a tubular member which will be formed into the device;selectively removing a portion of the tubular member material using alaser device; and applying jets of compressed fluid medium to thesurface of the tubular member after it is laser cut.
 24. The method ofclaim 23, wherein the fluid medium is air.